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About obesity

What’s the link between obesity and diabetes?

The link between obesity and type 2 diabetes is well established, with both conditions listed as comorbidities of the other.

5 min. read
Woman speaking to doctor

Insulin explained

Insulin is a naturally occurring hormone that regulates blood glucose in the body. Obesity – especially abdominal fat distribution – can lead to insulin resistance, where the body cannot produce enough insulin, or is unable to properly use the insulin it does produce. Insulin resistance can lead to high blood sugar levels, which greatly increases the risk of developing type 2 diabetes.

Insulin is necessary for carbohydrates, fat, and protein to be metabolised. Therefore, with the compromised insulin function that comes with type 2 diabetes, the risk of obesity also increases.

Because of the significant overlap between these two diseases, they share many of the same lifestyle changes – namely nutrition and physical activity – needed to help keep them in check. While lifestyle factors play an important role in treating obesity and diabetes, in some circumstances, other interventions such as pharmacotherapy may be required.

Individual risk of obesity

Obesity is increasingly common, with close to 2 billion people predicted to be living with obesity by 2035. Obesity develops due to excess body fat, taking the form of a chronic disease or long-lasting condition.

Obesity often suffers from the stigma of being considered a lifestyle disease. However, lifestyle is just one part of that equation. Everyone’s own body, metabolism, and genetics form a unique equation. Science has given us a better understanding of how different genetics are naturally predisposed to an increased risk of obesity.

Not only is obesity a major risk factor for type 2 diabetes, but it is also likely to increase the rate at which type 2 diabetes progresses. Therefore, maintaining a healthy body weight and avoiding weight gain is crucial for diabetes management and prevention. Every day that a person lives with excess weight also increases their risk of adverse cardiovascular outcomes such as heart attack and stroke.

Is obesity genetic?

When does overweight become obesity?

Obesity is a complex chronic disease in which abnormal or excess body fat impairs health, increases the risk of long-term medical complications and reduces lifespan. Obesity is defined using the body mass index (BMI; weight/height2). Obesity is defined as a BMI exceeding 30 kg/m2 and is subclassified into class 1 (30–34.9), class 2 (35–39.9) and class 3 (≥ 40). At the population level, health complications from excess body fat increase as BMI increases.

BMI is a tool to estimate body fat and screen for obesity and health risks. It can be calculated with a BMI calculator and classifies people as being underweight, overweight, and obese based on their height and weight. BMI is calculated by dividing weight in kilograms by height in meters and then comparing your result to the BMI classes. Body mass index (BMI) can also be correlated to type 2 diabetes risk.

There are six weight status categories:

What is a healthy BMI?

Underweight  below 18.5
Normal  18.5 - 24.9
Overweight  25 - 29.9
 Class I  30.0 – 34.9
 Class II  35.0 – 39.9
 Class III  Above 40

Find your BMI and health risks

Metric Imperial
Metric / Imperial

People who fall into the overweight category should talk to their doctor about how to slow the progression or potentially prevent obesity. If you are in obesity class I, II or III you should talk to a doctor about managing your obesity and your type 2 diabetes risk.

How to reduce your risk of obesity & type 2 diabetes

Nutrition and physical activity are key recommendations for reducing the risk or slowing the progression of obesity and type 2 diabetes. While weight management and nutrition can often seem straightforward on paper, it’s rarely as simple in practice. What works for one person might not work as effectively for another.

Our genetic variations mean we all store and spend energy differently. Even as we go about improving our health, our bodies and our metabolism react differently to our changing fitness levels, which means our approach – and often our nutrition – may also need to evolve.

Our ability to make healthy choices – such as being able to access and afford healthy food, or having the time and energy to engage in physical activity – is directly linked to our economies, our living situations, and the environments in which we live.

There is no one-size-fits-all solution to health. What is right at the beginning of a journey might not be right down the line. That means you need to find the right solution, or the right level of change for you. Nobody can achieve everything overnight, so start with what’s manageable and work towards realistic improvement goals.

And remember, nobody needs to take that journey alone. Beyond the advice below, your starting point should always be to seek advice from your doctor.


The chance of inheriting obesity through genetics is estimated between 40-70%

-McPherson R. Genetic contributors to obesity


While nutrition is a key driver of health for everybody, regardless of body size, there is no one-sizefits-all healthy eating plan. You should choose an eating plan that supports your best health and that you can maintain long term.

Short-term diets, or severely restricting the amount you eat, can cause metabolic adaptation which may make any weight loss difficult to sustain after the period of dietary restriction.

Talk to your healthcare provider about how a healthy food plan can help you support your health goals. See a registered dietitian for an individualised approach and support.

Read more on managing diabetes and obesity:

How to manage diabetes with diet

Obesity management programme: How to find the best exercises for you

Diabetes & obesity – what you need to know

Physical activity

Physical activity It’s recommended that everyone should exercise moderately for at least 30 minutes per day, five times a week – not only to manage weight and blood sugar, but also to reduce cardiovascular risk. For some people, this could be high-intensity training, for others, it might be light yoga.

Everybody is different, and the level of physical activity you take on needs to be achievable for your existing level of fitness. Taking on too much too soon can lead to injury or exhaustion. Motivation also tends to be more sustainable with incremental progress.

If you haven’t engaged in physical activity in a long time, start with something light, like a daily walk at a nearby park. Increase distance and pace from week to week so that you keep your pulse up and gradually increase your aerobic fitness. The important thing is to maintain progress. As your fitness improves, so too will your metabolism. To keep improving your health, you should gradually increase the intensity of your physical activity.

Regular physical activity supports a wide range of health benefits in adults across all BMI categories, even without weight loss. Aerobic and resistance exercise can favour the maintenance or improvements in cardiorespiratory fitness, mobility, strength, and muscle mass during weight management.

Read more on managing diabetes and obesity:

Obesity management programme: How to find the best exercises for you

How to manage diabetes through exercise

Psychological factors 

Depression and insomnia can both be linked to weight gain. The health of the body and mind are intrinsically linked – when one starts to falter, it may invariably impact the other.

With mental health, it can also be difficult to pinpoint the exact cause of symptoms or make changes on your own, so it’s advisable to seek guidance from your doctor if problems persist.

8 ways to manage stress and overcome mental barriers to weight loss

Always talk to your doctor

Obesity is complex and difficult to manage. Seek the advice of your doctor when considering lifestyle changes and to better understand the support available.

Obesity diagnosis and treatment: Why it’s important

Find your local weight management provider

Talk to your weight management provider about treatment options that could prevent the weight you lose from coming back.

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